A New Kind of Flu Vaccine Is Coming This Fall — Here’s What to Know

The U.S. Food and Drug Administration (FDA) has approved mFLUSIVA (mRNA-1010), Moderna’s new seasonal flu vaccine and the first mRNA-based flu shot licensed in the United States. The approval covers adults 50 and older and follows a unanimous recommendation from the FDA’s Vaccines and Related Biological Products Advisory Committee.

Moderna CEO Stéphane Bancel called it the company’s fourth approved product in the U.S. and pointed to it as evidence of the continued reach of Moderna’s mRNA platform, adding that flu remains a significant public health challenge and that the vaccine gives older adults an important new prevention option.

How the Approval Was Backed Up

For adults ages 50 through 64, the approval rests on a Phase 3 trial that enrolled 40,805 adults across 11 countries, comparing mFLUSIVA against a standard-dose active comparator. The trial measured safety and reactogenicity, along with how well the vaccine prevented lab-confirmed influenza-like illness caused by influenza A or B. The trial showed 26.6% relative vaccine efficacy compared with the standard-dose comparator, with fewer confirmed influenza-like illness cases in the mRNA-1010 group.

For adults 65 and older, the approval came through an accelerated pathway based on a separate trial of 2,992 U.S. adults that compared immune response to a high-dose inactivated flu vaccine, rather than measuring prevention of illness directly. Confirmation of clinical benefit in this age group will depend on results from a postmarketing trial still to come.

A Bumpy Path to the Finish Line

The approval caps off an unusually rocky regulatory process. The FDA initially declined to even review Moderna’s application over questions about the design of the Phase 3 trial. The agency later reversed course and agreed to review the application following a meeting with Moderna.

Weighing the Side Effects

Moderna’s safety information for mFLUSIVA lists injection site pain, tenderness, swelling and redness, along with fatigue, headache, muscle pain, joint pain, chills, nausea and fever as reported side effects. Severe allergic reactions are rare but can occur, typically within an hour of vaccination, which is why providers may ask patients to stay for observation afterward. People with a history of severe allergic reaction to a previous vaccine dose or Guillain-Barré syndrome following a flu shot should discuss that history with their provider before getting mFLUSIVA.

What Comes Next

Moderna expects mFLUSIVA to reach select retailers within the coming weeks and to be broadly available for the 2026-2027 respiratory virus season, joining the company’s existing lineup of Spikevax, mRESVIA and mNEXSPIKE. The vaccine has also been accepted for regulatory review in the European Union, Canada and Australia, with additional international submissions planned later this year.